Concurrent tolerance design

Technical drawings are constituted by three components that are strongly correlated: the geometry showing the part shape, the dimensions defining the part volume and the tolerances establishing the variability of the two previously described components. A general methodology to assign the tolerances, especially geometric tolerances, to all the components of an assembly has not been clearly defined up to now. This is probably due to the complexity of the problem and to the existing gap between the existing standards and the industrial designers' common practices. In this work, a new general methodology to assign dimensional and geometric tolerances to all the components of an assembly with a concurrent design approach is proposed. It takes into consideration the relationships between tolerances and a set of design principles that have been naturally extracted from the standards and literature and from a deep discussion with the Italian Association of Industrial Designers. In order to demonstrate and validate the proposed approach, the methodology has been applied to two real case studies: a volumetric gear pump and a pneumatic actuator.